Researchers create world’s smallest battery

Nanotechnology researchers at Sandia National Laboratories have created a benchtop version of the world’s tiniest battery, with its anode one seven-thousandth the thickness of a human hair.

The team at the Center for Integrated Nanotechnologies (CINT), led by researcher Jianyu Huang, formed the tiny, rechargeable lithium-ion battery inside a transmission electron microscope (TEM) to better study the anode’s characteristics.

As reported in the 10 December issue of Science, Huang said of the work: “This experiment enables us to study the charging and discharging of a battery in real-time and at atomic-scale resolution, thus enlarging our understanding of the fundamental mechanisms by which batteries work.”

According to the team at CINT, nanowire-based materials in lithium-ion batteries offer the potential for significant improvements in power and energy density over bulk electrodes, so more stringent investigations of their operating properties should improve new generations of plug-in hybrid electric vehicles, laptops and mobile phones.

“What motivated our work,” says Huang, “is that lithium-ion batteries [LIB] have very important applications, but the low energy and power densities of current LIBs cannot meet the demand.

“To improve performance, we wanted to understand LIBs from the bottom up, and we thought in-situ TEM could bring new insights to the problem.”

Formerly unobserved increase in length and twist of the anode in a nanobattery. (Courtesy DOE Center for Integrated Nanotechnologies)

The tiny battery created by Huang and co-workers consists of a single tin oxide nanowire anode 100 nanometres in diameter and 10 micrometres long, a bulk lithium cobalt oxide cathode 3mm long, and an ionic liquid electrolyte.

The researchers unexpectedly found that the tin oxide nanowire rod nearly doubles in length during charging — far more than its diameter increases — a fact that could help avoid short circuits that may shorten battery life, said Huang.

“This is the closest view to what’s happening during the charging of a battery that researchers have achieved so far.”

“The methodology that we developed should stimulate extensive real-time studies of the microscopic processes in batteries and lead to a more complete understanding of the mechanisms governing battery performance and reliability,” he said. “Our experiments also lay a foundation for in-situ studies of electrochemical reactions, and will have broad impact in energy storage, corrosion, electrodeposition and general chemical synthesis research field.”

CINT is a Department of Energy research facility jointly operated by Sandia and Los Alamos national laboratories.